"On estim.pay. to make for next year's return" do I need to make the four payments. It states if we owe more than 1000 in 2017, is this mandatory?

[AnthonyC · Accepted solution]

The program produces these forms more as a convenience for you to make the payments.  You are not locked into those specific payments.  The program will produce them automatically if you owed tax as the government requires you to withhold enough tax to cover your tax liability or make estimated tax payments.  If you don't have enough withholding and you don't make estimated tax payments, then the IRS can charge you with an underpayment penalty.  There are exceptions to this penalty:  " Generally, most taxpayers will avoid this penalty if they either owe less than $1,000 in tax after subtracting their withholding and estimated tax payments, or if they paid at least 90% of the tax for the current year or 100% of the tax shown on the return for the prior year, whichever is smaller."

If you owed tax this year because of a one-time event and you won't owe next year, then you can decline to send any payments.  You can also decline to send the payments even if you will owe tax next year, but you may be assessed an underpayment penalty.  You can view more information about this penalty at the link below.

https://www.irs.gov/taxtopics/tc306.html